This implements all pending specs, and adds additional coverage for the
following functionality:

* Normal status creation
* Creating a reply status
* Creating a sensitive status
* Creating a status with spoiler text
* A status with no spoiler text gets an empty string for spoiler text
* Creating a status with custom visibility
* Creating a status for an application
* Processing mentions
* Processing Hashtags
* Pinging PuSH hubs
* Crawling links
* Attaching media

There are currently not specs for the two media validations that are performed
by `PostStatusService`. This adds specs for the validations that ensure that you
cannot attach more than four files, and that a status cannot have both image and
video attachments.

This adds the ability to filter user signup with a whitelist
instead of or in addition to a blacklist.

Fixes #817

Fix anchor tags in some wikipedia URLs being matches as a hashtag

StreamEntry model. Simply render Salmon slaps as they are needed

if account lock info was up to date, otherwise re-do the FollowService
with now updated information

Try to fix Travis CI setup

redis-backed "mentions" timeline as redundant (given notifications)

affected, replaced onClick handler with onMouseUp/Down to detect text
selection not trigger onClick handler then

application website validation, don't link to app website if website isn't set,
also comment out animated boost icon from #464 until it's consistent with non-animated version

A couple of places were using "reblog" rather than "boost" - this updates them to match the web UI